From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7735BC433DB for ; Mon, 1 Mar 2021 15:12:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4316564DFB for ; Mon, 1 Mar 2021 15:12:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236960AbhCAPMT (ORCPT ); Mon, 1 Mar 2021 10:12:19 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46051 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236895AbhCAPIs (ORCPT ); Mon, 1 Mar 2021 10:08:48 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614611242; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3CcxvPbENRoxnpPYUhLzxCww37f6skYKB+CD+PRX/BM=; b=Ch2p7rc+kWj9s4Ru6vmKLAg2TTFvdLa2rE9d5VvlNeLzl3KPHQjHQg+sBCXjEGESsZgCJI Um2gy+41xkW9qqgOgy7nsgV2tjMIDCNCufXpXof0zvhG+qnEaialdvecSarIq9dH4P+ijF Lyz/ZjQgukuHhNg3dYBtHjDxkPfa3oc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-251-t7bwRF9dOFm6QxJxl1AHCQ-1; Mon, 01 Mar 2021 10:07:18 -0500 X-MC-Unique: t7bwRF9dOFm6QxJxl1AHCQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B8B47107ACE6; Mon, 1 Mar 2021 15:07:15 +0000 (UTC) Received: from ovpn-114-130.ams2.redhat.com (ovpn-114-130.ams2.redhat.com [10.36.114.130]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7AC695C3E5; Mon, 1 Mar 2021 15:07:12 +0000 (UTC) Message-ID: <51bd5e035546937b8c46264b52e149f0331d0b60.camel@redhat.com> Subject: Re: possible deadlock in ipv6_sock_mc_close From: Paolo Abeni To: Chuck Lever , syzbot Cc: Bruce Fields , "David S. Miller" , "dsahern@kernel.org" , Jakub Kicinski , LKML , Linux NFS Mailing List , Linux-Net , "yoshfuji@linux-ipv6.org" , "syzkaller-bugs@googlegroups.com" Date: Mon, 01 Mar 2021 16:07:11 +0100 In-Reply-To: <974A6057-4DE8-4C9A-A71E-4EC08BD8E81B@oracle.com> References: <0000000000001d8e2c05bc79e2fd@google.com> <974A6057-4DE8-4C9A-A71E-4EC08BD8E81B@oracle.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Mon, 2021-03-01 at 14:52 +0000, Chuck Lever wrote: > > On Mar 1, 2021, at 8:49 AM, syzbot wrote: > > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: eee7ede6 Merge branch 'bnxt_en-error-recovery-bug-fixes' > > git tree: net > > console output: https://syzkaller.appspot.com/x/log.txt?x=123ad632d00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=e2d5ba72abae4f14 > > dashboard link: https://syzkaller.appspot.com/bug?extid=e2fa57709a385e6db10f > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=109d89b6d00000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12e9e0dad00000 > > > > The issue was bisected to: > > > > commit c8e88e3aa73889421461f878cd569ef84f231ceb > > Author: Chuck Lever > > Date: Tue Nov 3 20:06:04 2020 +0000 > > > > NFSD: Replace READ* macros in nfsd4_decode_layoutget() > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13bef9ccd00000 > > final oops: https://syzkaller.appspot.com/x/report.txt?x=107ef9ccd00000 > > console output: https://syzkaller.appspot.com/x/log.txt?x=17bef9ccd00000 > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+e2fa57709a385e6db10f@syzkaller.appspotmail.com > > Fixes: c8e88e3aa738 ("NFSD: Replace READ* macros in nfsd4_decode_layoutget()") > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 5.11.0-syzkaller #0 Not tainted > > ------------------------------------------------------ > > syz-executor905/8822 is trying to acquire lock: > > ffffffff8d678fe8 (rtnl_mutex){+.+.}-{3:3}, at: ipv6_sock_mc_close+0xd7/0x110 net/ipv6/mcast.c:323 > > > > but task is already holding lock: > > ffff888024390120 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1600 [inline] > > ffff888024390120 (sk_lock-AF_INET6){+.+.}-{0:0}, at: mptcp6_release+0x57/0x130 net/mptcp/protocol.c:3507 > > > > which lock already depends on the new lock. > > Hi, thanks for the report. > > Initial analysis: > > c8e88e3aa738 ("NFSD: Replace READ* macros in nfsd4_decode_layoutget()" > changes code several layers above the network layer. In addition, > neither of the stack traces contain NFSD functions. And, repro.c does > not appear to exercise any filesystem code. > > Therefore the bisect result looks implausible to me. I don't see any > obvious connection between the lockdep splat and c8e88e3aa738. (If > someone else does, please let me know where to look). I agree the bisect result is unexpected. This looks really as an MPTCP-specific issue, likely introduced by: 32fcc880e0a9 ("mptcp: provide subflow aware release function") and should be fixed inside MPTCP. Cheers, Paolo